Grass pea dual purpose dry matter and seed yields in rainfed conditions across diverse environments

Grass pea (Lathyrus sativus L.) stands out as an excellent choice for sustainable agriculture, thanks to its favorable agronomic characteristics, including a robust root system that penetrates deeply into the soil and its resilience against various biotic and abiotic stressors. In this study, dry-matter yield and seed yield of 16 grass pea genotypes were evaluated in rain-fed conditions at "Gachsaran", "Mehran", "Kuhdasht", and "Shirvan-Chardavol" locations in Iran for three consecutive years. The experimental field trials were carried out using a randomized complete block design, and each experimental setup was replicated three times. The descriptive statistics showed a mean value of 4.030 (ton/ha) and 1.530 (ton/ha), with phenotypic coefficients of 54.77 and 61.56 for dry-matter yield and seed yield, respectively. The projection of geographical, climatic, and edaphic variables into yield measurements depicted remarkable divergence among the four studied environments. Elevation exerts a greater influence on both dry matter and seed yields in the Mehran location as compared to other environments. The climatic factors of rainfall and relative humidity played an important role in "Gachsaran" and "Shirvan-Chardavol", respectively. While for seed yield, the temperature-related attributes were more significant in the "Mehran" location. Low broad-sense heritability was observed, and the R² for genotype-environment interaction showed the existence of GEI for dry-matter yield (0.126) and seed yield (0.223). Both AMMI1 and AMMI2 could recognize unstable genotypes from other ones, and both AMMI's identified genotypes G10 and G3 as high-yielding and stable genotypes. BLUP-based stability indices revealed G10 and G13 as superior genotypes for seed yield and dry-matter yield, respectively. Three and two mega-environments were identified using a GGE biplot for dry-matter yield and seed yield. For dry-matter-identified mega-environments, the G1, G13, and G2, and for seed-yield-recognized mega-environments, the G10 and G15 can be introduced. "Mehran" and "Gachsaran" out of the studied locations possessed diverse distributions considering dry-matter yield and seed yield and for further GE interaction studies, it is better to establish adaptability trials in these locations. The study concludes that for the promotion of sustainable agriculture in rain-fed regions, taking into account the influence of environmental factors, cultivation of the identified grass pea genotypes holds promise.